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Old 12-13-2013, 09:27 AM   #127
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Originally Posted by dkottum View Post

Does the Chrysler 300 have this system?
Not that I know of. As Steve said, it would be unlikely on a vehicle not marketed specifically as a tow vehicle. I have read about this system in other articles about towing, but I am not aware of any implementations. Generally, once you have a stability control system it would be easy to add this algorithm. I do have stability control, however.
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Old 12-13-2013, 09:32 AM   #128
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Thanks for posting that Steve. I found this summation of the parameters for stability to be quite concise and helpful.

Instability increases as:

QUOTE
1)the mass of the trailer (relative to the vehicle’s mass)
increases,
2) the center of gravity of the trailer moves rearward,
3) the moment of inertia of the trailer increases,
4) cornering stiffness of trailer tires decreases,
5) cornering stiffness of the vehicle’s rear tires decreases
6) the distance from the vehicle rear axle to the hitch point increases,
7) vehicle wheelbase decreases.

Even for a specific vehicle-trailer combination, most of these parameters can be greatly altered by changing parameters that are in control of the user, such as weight distribution or tire type and tire pressure.
END QUOTE

I had not given much thought to #4 in the past. I will see what I can find out about my Michelins. As to #5 I am wondering if the TV suspension itself is also a factor. e.g. Limiting side to side slop.
For item 6 - isn't that a key part of the value proposition of the HaHa and PP hitches? Virtual projection of the pivot point almost TO the rear axle? There's a penalty to be paid with weight that whether you count some/all as tongue weight must still count toward payload, but the stability and no-sway are the big benefit. Everything has trade offs.
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Old 12-13-2013, 09:36 AM   #129
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Quote:
Originally Posted by mstephens View Post
Thanks for posting that Steve. I found this summation of the parameters for stability to be quite concise and helpful.

Instability increases as:

QUOTE
1)the mass of the trailer (relative to the vehicle’s mass)
increases,
2) the center of gravity of the trailer moves rearward,
3) the moment of inertia of the trailer increases,
4) cornering stiffness of trailer tires decreases,
5) cornering stiffness of the vehicle’s rear tires decreases
6) the distance from the vehicle rear axle to the hitch point increases,
7) vehicle wheelbase decreases.

Even for a specific vehicle-trailer combination, most of these parameters can be greatly altered by changing parameters that are in control of the user, such as weight distribution or tire type and tire pressure.
END QUOTE

I had not given much thought to #4 in the past. I will see what I can find out about my Michelins. As to #5 I am wondering if the TV suspension itself is also a factor. e.g. Limiting side to side slop.
I think is something very important, and as a matter of fact, I have heard of some people complaining of the newer 1500 Ram trucks with the coil spring rear suspension not being as stable as some of the parallel leaf spring trucks.

This I believe could be attributed to greater side to side movement of the rear axle under the truck because of play, or looseness in the panhard rod bushings.

I learned long ago that maximum stability of a given rig is obtained when both the trailer tires and the rear axle tires of the tow vehicle are run at maximum air pressure (maximum stiffness).

In addition, I learned long ago that too much air pressure in the front axle tires of a tow vehicle, can cause instability towing a trailer. What it does, IMO, is it creates an condition where the steering response is actually too fast, and therefore creates a situation where minor steering inputs actually cause the trailer to be whipped, so to speak.
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Old 12-13-2013, 09:40 AM   #130
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That's a great question SteveSueMac. I would not be qualified to answer. I hope someone who is qualified does answer. I can say that if a projected pivot is mathematically equal to a physical pivot, that would make a VERY convincing argument to me for these kind of hitches.
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Old 12-13-2013, 09:44 AM   #131
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Originally Posted by SteveSueMac View Post
For item 6 - isn't that a key part of the value proposition of the HaHa and PP hitches? Virtual projection of the pivot point almost TO the rear axle? There's a penalty to be paid with weight that whether you count some/all as tongue weight must still count toward payload, but the stability and no-sway are the big benefit. Everything has trade offs.
In my experience, yes that is exactly what the pivot point projection hitches do. There is no better hitch configuration built at this time, again in my experience, for towing stability.

However, as you will find in these forums, such as the weight penalty, the hitching and unhitching difficulties in some situations, they are not without issues, and then there's the cost factor. And then, the Hensley actually has some issues with parts breaking.

And another thing I would mention is the PP hitches mandate that the trailer brakes work perfectly, or problems will arise.

Like everything in this world, there are no free lunches.
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Old 12-13-2013, 09:48 AM   #132
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I think is something very important, and as a matter of fact, I have heard of some people complaining of the newer 1500 Ram trucks with the coil spring rear suspension not being as stable as some of the parallel leaf spring trucks.

This I believe could be attributed to greater side to side movement of the rear axle under the truck because of play, or looseness in the panhard rod bushings.
On this parameter, I offer the following observation. Many tall vehicles, like my Suburban, are easy to "push" side to side by simply standing at the rear and pushing on the fender. Comparing my 'Burb to the 300, the 300 is far, far stiffer. It might be intuitive to say that a high CG and a loose suspension are bad, and a low CG and a tight suspension are good. For this reason, I have to question the idea offered by some that "Pickup trucks are designed for towing." If so, they ought not be so high, and they ought not be so loose in the rear. Both are easy to control by the manufacturer. Isn't the "high ride" more of an aesthetic than anything else? PUTs are getting high and higher each year (it seems).

Also, examine tires of the PUT versus tires on the sport sedan. They are designed for different purposes. I believe my low profile stiff and sticky tires are better for towing that the higher profile less sticky tires of the typical PUT. It's a reasonable question, I think.
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Old 12-13-2013, 09:49 AM   #133
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Perhaps that is why the Load E tires on the Dodge Ram 2500HD are not run at the full 80 psi on the sidewalls. The front tires are to be at 60psi which gives the tires the same load rating as the front axle and the rear tires are to be inflated to 70 psi to have the same load rating as the rear axle. The Hensley hitch had moved some weight to the front wheels as the unhitched front axle weight is 4,880 pounds just driving around.

Loaded for camping with the 25FB, the front axle rated 5,500 pounds was carrying 4,820 pounds and the rear axle rated 6,010 pounds was carrying 5,300 pounds.

When the truck is empty with no trailer, they suggest 45psi on the rear tires so your kidneys and teeth don't fall out from the stiff ride at 70 psi unloaded.

Due to different anatomy, my wife definitely likes the unladen ride better with the rear ties at 45psi.
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Old 12-13-2013, 09:49 AM   #134
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And another thing I would mention is the PP hitches mandate that the trailer brakes work perfectly, or problems will arise.
------------------------------
That's a new argument I am unaware of. Can you elaborate just a tad for clarity? What sort of problem?
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Old 12-13-2013, 10:00 AM   #135
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Pointing once more at the argument that PUTs are "designed for towing" let's try a little comparison regarding the 7 factors discussed in stability. ADV PUT means the advantage is most likely with the PickUp Truck. ADV SEDAN means the advantage is more likely with a SEDAN like the 300. NEUTRAL means it is a trailer property which applies to either vehicle.

1)the mass of the trailer (relative to the vehicle’s mass) increases, ADV PUT
2) the center of gravity of the trailer moves rearward, NEUTRAL
3) the moment of inertia of the trailer increases, NEUTRAL
4) cornering stiffness of trailer tires decreases, NEUTRAL
5) cornering stiffness of the vehicle’s rear tires decreases ADV SEDAN
6) the distance from the vehicle rear axle to the hitch point increases, ADV SEDAN
7) vehicle wheelbase decreases. TOSSUP (the 300 WB is 120")

Not too bad for the SEDAN.

NOTE: I think there is a very significant difference in meaning between the idea of "designed for towing" and the idea "marketed for towing." Is there really a vehicle out there that was "designed for towing?"
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Old 12-13-2013, 10:14 AM   #136
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Originally Posted by SteveH View Post

In my experience, yes that is exactly what the pivot point projection hitches do. There is no better hitch configuration built at this time, again in my experience, for towing stability.

However, as you will find in these forums, such as the weight penalty, the hitching and unhitching difficulties in some situations, they are not without issues, and then there's the cost factor. And then, the Hensley actually has some issues with parts breaking.

And another thing I would mention is the PP hitches mandate that the trailer brakes work perfectly, or problems will arise.

Like everything in this world, there are no free lunches.
I wonder if PullRite makes their hitch for sedans?? That's an actual (not projected) pivot point at the axle.
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Old 12-13-2013, 10:21 AM   #137
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Originally Posted by mstephens View Post
And another thing I would mention is the PP hitches mandate that the trailer brakes work perfectly, or problems will arise.
------------------------------
That's a new argument I am unaware of. Can you elaborate just a tad for clarity? What sort of problem?
Hensley bump. I think it's a function of the brake controller setup where the trailer brakes don't fire before the TV brakes. That ends up pushing the trailer toward the TV and "bumps" it, misaligning the hitch head. I've personally never experienced it but I think Steve has had trouble with that in his Dodge.
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Old 12-13-2013, 10:22 AM   #138
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I wonder if PullRite makes their hitch for sedans?? That's an actual (not projected) pivot point at the axle.
Just looking at the pictures of it, it doesn't look like it would fit under my car. I don't see a way of attaching it. Looks like it is designed around a fundamental "frame" concept.
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Old 12-13-2013, 10:26 AM   #139
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Hensley bump. I think it's a function of the brake controller setup where the trailer brakes don't fire before the TV brakes. That ends up pushing the trailer toward the TV and "bumps" it, misaligning the hitch head. I've personally never experienced it but I think Steve has had trouble with that in his Dodge.
There are many conditions where the TT can end up pushing the TV, other than braking. Certain dips, downhill and other conditions could cause a temporary condition of the "TT pushing the TV."

Is this "misalignment" temporary? Does one have to stop and fix it?

I don't mean to open a can of worms. Just wondering.
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Old 12-13-2013, 01:15 PM   #140
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I wonder if PullRite makes their hitch for sedans?? That's an actual (not projected) pivot point at the axle.
I was understanding that PullRite was out of business?
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